Facebook users need to be very careful these days. The popular social networking site has been hit with a new wave of malware that pretends to be one of the thousands of third party apps available on the site. One of the most dangerous is the newest version of the Koobface worm, which turns the machines it infects into zombies and adds them to a botnet.

Another rogue program that made the rounds last week, causing havoc as it did so was an app called “Facebook-closing down!” which sent fake notifications to users saying one of their friends had reported them to Facebook for terms and services violations. Anyone who clicked on the link in the fake alert was directed to the app, which then sent the same fake alerts to all their friends. Since the fake alerts actually named the friend who allegedly did the reporting, a lot of drama and hurt feelings ensued.

A third malicious app going around is called “Error Check System” which sent fake alerts from the user’s friends saying they had experienced problems accessing that users profile. Like the “Facebook-closing down!” app, clicking on the link sends the same fake alerts to everyone in the users friends list. Experts say both apps harvested email addresses and other personal info as they spread.

Facebook has since shut down both apps, but you can be sure new ones will pop up in their place. The only way to protect yourself is to be careful of what apps you use, and click with caution. A little common sense helps as well – if someone actually were to report you on Facebook or any other site, you would never be told exactly who it was. Enjoy Facebook, but be picky when it comes to using the site’s third party apps.